Tape feeder, electronic component mounting apparatus using the same, and method of feeding electronic components

ABSTRACT

A tape feeder feeds electronic components by advancing a tape intermittently. The tape feeder comprises a motor controller for controlling a motor, which rotatively drives a sprocket to advance the tape, and a communication unit for receiving a control signal from a control unit of an electronic component mounting apparatus and transmitting a control parameter such as a rotating speed, an amount of rotation, and acceleration and deceleration pattern to the motor controller. The tape feeder has such a structure that a tape advancing speed and an amount of tape advancement are easily changeable according to a type of the electronic components by changing the control parameter of the rotating speed and the amount of rotation of the motor. In addition, the tape feeder is adaptable for correction of the amount of rotation according to a result of measurement of pin position of the sprocket, so as to properly interrupt turning of the sprocket at the correct stop position for accurate positioning of the electronic components into the right pick-up location all the time.

FIELD OF THE INVENTION

The present invention relates to a tape feeder for feeding electroniccomponents borne on a tape by advancing them intermittently to a pick-uplocation in an electronic component mounting apparatus. The inventionalso relates to a method of advancing the tape.

BACKGROUND OF THE INVENTION

In an electronic component mounting apparatus, a tape feeder is used asa commonly known method of feeding electronic components into a pick-uplocation of a nozzle of transfer head. In this method, a tape bearingthe electronic components is pulled out of a supply reel, and fed to thenozzle by advancing it intermittently in synchronization with mountingtiming of the electronic components. This tape feeder intermittentlyadvances the tape only a predetermined amount by rotating a sprocket,which is in engagement with feedholes perforated in the tape.

In using tape feeders, it is a general practice to prepare a number oftape feeders of the same kind, and any of these tape feeders are mountedto a plurality of electronic component mounting apparatuses as needed.In other words, when taking a certain feeder mounting base of theelectronic component mounting apparatus as an example, a number of thetape feeders that are adaptable for installation are mounted to it.These tape feeders supply electronic components to the transfer head byadvancing the tapes toward a pick-up location.

Because there are various types of electronic components havingdifferent sizes, it is necessary to prepare many kinds of tape feedersaccording to widths of the tapes that bear the electronic components aswell as mount pitches of the electronic components along the tapes.However, the conventional tape feeder requires a complicated operationto change a distance of advancement of the sprocket, when the taperequires a different advancing pitch due to a difference in the type ofelectronic components even if the tape used has the same dimensionwidthwise. In addition, it is desirable to set an advancing speed andacceleration of the tape appropriately according to the type ofelectronic components, since there is a risk that the components willmove out of their normal positions and result in a failure to stablypick-up the components depending on the type of electronic componentsand the operation during advancement of the tape. However, it is notpossible to make such a setting of the tape advancing speed easily withthe conventional tape feeders.

In many of these tape feeders, there are tape advancing errors due toindividual instrumental errors, and a position of the advanced tape doesnot always come into alignment with the pick-up location of the transferhead. Mechanical adjustments are therefore necessary, such as alignmentof a positioning dowel for each of the tape feeders in the prior art,and they require a great effort if many tape feeders are involved.

SUMMARY OF THE INVENTION

In an electronic component mounting apparatus, a tape feeder supplieselectronic components to a pick-up location by intermittently advancinga tape bearing the electronic components. The tape feeder comprises: asprocket in engagement with feedholes perforated at regular pitches inthe tape, for advancing the tape; a drive mechanism including a motor asa driving force for rotatively driving the sprocket; and a motorcontroller for controlling the motor. The tape feeder further has any ofthe following features.

-   A) The tape feeder is provided with a communication unit for    receiving a control signal from an external device.-   B) The tape feeder draws data on an amount of rotation of the motor    corresponding to a position where turning of the sprocket is    interrupted, based on a result of measurement of a pin position of    the sprocket.

In a method of feeding electronic components using the tape feederprovided with the above feature “A”, the tape feeder changes controlparameter of the motor by communicating a control signal between themotor controller for controlling the motor and a control unit in theelectronic component mounting apparatus during the step of advancing thetape intermittently by turning the sprocket with the drive mechanismhaving driving force of the motor.

A method of feeding electronic components using the tape feeder of theabove feature “A” comprises measuring a pin position of the sprocketwhen the sprocket is interrupted from turning, as an electroniccomponent is advanced to a pick-up location. Data on an amount ofrotation of the motor corresponding to the position where turning of thesprocket is interrupted is drawn based on a result of measurement of thepin position.

In addition, an electronic component mounting apparatus includes thetape feeder provided with any of the above features “A” and “B”.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view depicting an electronic component mountingapparatus provided with a tape feeder according to an exemplaryembodiment of the present invention;

FIG. 2 is a side view depicting the tape feeder according to theexemplary embodiment of this invention;

FIG. 3 is a block diagram showing a structure of control system of thetape feeder according to the exemplary embodiment of this invention;

FIG. 4 is a partial side view depicting the tape feeder according to theexemplary embodiment of this invention;

FIG. 5A is a partial plan view depicting the tape feeder according tothe exemplary embodiment of this invention;

FIG. 5B is an enlarged view of a part of FIG. 5A depicting a pin and thevicinity thereof;

FIG. 6A and FIG. 6B are tables respectively showing data on stopposition and data on pick-up location of the tape feeder according tothe exemplary embodiment of this invention; and

FIG. 7 is expository illustration showing a method of adjusting the stopposition and the pick-up location of the tape feeder according to theexemplary embodiment of this invention.

DETAILED DESCRIPTION OF THE INVENTION

First of all, a structure of an electronic component mounting apparatusis described with reference to FIG. 1. In FIG. 1, the electroniccomponent mounting apparatus 1 (hereinafter referred to as “mountingapparatus”) comprises component feeder unit 2 for supplying electroniccomponents. The component feeder unit 2 has a plurality of tape feeders4 mounted to a top surface of feeder base 3. Any of the tape feeders 4pulls out carrier tape 7 bearing electronic components from supply reel6 installed on truck 5 placed under the feeder base 3. The tape feeder 4delivers the electronic components borne thereon to a pick-up locationof transfer head 8.

Head drive unit 11 actuates the transfer head 8, which then mounts anelectronic component picked up from the tape feeder 4 onto substrate 10placed on conveyor track 9. Control unit 14 controls the head drive unit11. Storage unit 15 stores various data necessary for the transfer head8 to perform mounting operation and the tape feeder 4 to performadvancing operation of the tape.

The data include tape data 15A, stop position data 15B, pick-up locationdata 15C, and mounting position data 15D, as shown in FIG. 3.

The tape data 15A represent such data as an advancing pitch and anadvancing speed for intermittent advancement of the carrier tape 7, anacceleration and deceleration pattern during the intermittentadvancement, and the like. This data is pre-set individually for eachkind of the carrier tapes 7.

The stop position data 15B is correction data used to alleviatedeviation or displacement of a stop position of the tape during theintermittent advancement due to instrumental error inherent in each ofthe tape feeders. The electronic components borne on the carrier tape 7are precisely aligned with the pick-up location by making a correctionwith this data. In this exemplary embodiment, this correction is made ondeviation of the pin position of the sprocket that forwards the tape ina direction of the tape advancement.

The pick-up location data 15C is data representing a pick-up location ofthe tape feeder 4 where the transfer head 8 sucks and picks up theelectronic components. The pick-up location data is prepared in advancefor each of the tape feeders, so as to make a correction of theinstrumental error inherent in each of the tape feeders. In thisexemplary embodiment, the correction is made due to deviation ordisplacement in a direction orthogonal to the direction of the tapeadvancement (among deviations in various directions) of the pin positionof the sprocket, by aligning a pick-up location of the transfer head 8.

The mounting position data 15D is data relating to coordinates of amounting position of the electronic component in the substrate 10.

Camera 12 is installed above the pick-up location of the tape feeder 4.The camera 12 takes a photographic image of the pick-up location and thevicinity thereof, and recognition unit 13 performs a recognition processof the photographic image data. Through this process, the recognitionunit 13 discerns a location of a feedhole of the carrier tape 7, a pinposition of the sprocket for advancing the tape, and the like, so as todetect an extent of deviation, or displacement, from the regularposition. The control unit 14 calculates stop position data and pick-uplocation data based on the amount of deviation of each of the pinpositions as a result of the detection transferred to the control unit14.

Referring now to FIG. 2, FIG. 3 and FIG. 4, tape feeder 4 will bedescribed next. As shown in FIG. 2, the tape feeder 4 comprises mainbody 4A having a rectangularly slender shape and fixture unit 4Binstalled under the main body 4A. The main body 4A is mounted parallelto an upper surface of the feeder base 3, and the fixture unit 4B ispositioned securely by engaging it to one end of the feeder base 3.Feeder control unit 24 built into the main body 4A is connected with thecontrol unit 14 of the mounting apparatus 1 through connector 28provided in the fixture unit 4B. The storage unit 15 transfers data tothe feeder control unit 24 via the control unit 14, including data suchas the tape data 15A and the stop position data 15B that are necessaryfor controlling operation of the tape feeder 4.

The tape feeder 4 is provided with sprocket 21 at the forward end. Thesprocket 21 has pins 21A at regular pitches around its periphery forengaging feedholes 7B (refer to FIG. 7) provided also at regular pitchesalong the carrier tape 7 for advancement of the tape. In addition, thesprocket 21 is provided with toothed surface 21 B on its side (refer toFIG. 4) engaging a bevel gear 23 attached to a drive shaft of motor 22.The bevel gear 23 and the toothed surface 21B compose a drive mechanismthat drives sprocket 21.

The motor 22, when rotatively driven, turns the sprocket 21, whichadvances the carrier tape 7. This advancement pulls out the carrier tape7 from the supply reel 6. The pulled-out carrier tape 7 is guided intothe tape feeder 4 from its rear end, and moved forward along atape-feeding passage.

The motor 22 used in this preferred embodiment is a type that is capableof controlling a rotation speed and an amount of rotation, such as aservomotor. An advancing speed and an advancing pitch for intermittentadvancement of the carrier tape, a stop position during the intermittentadvancement, and the like can be set freely as desired by controllingthe rotation speed and the amount of rotation of the motor 22. The motor22 is also provided with an encoder with the capability of detecting anabsolute position, and it can detect individually a rotationaldisplacement of each of the pins 21A on the sprocket 21.

There is a pick-up location at the forward end of the tape feeder 4,where the transfer head 8 picks up electronic components. The carriertape 7 guided here is advanced intermittently under cover plate 29placed on the upper surface of the forward end. The transfer head 8picks up an electronic component 16 disposed in a recess 7A of thecarrier tape 7 through a cutout portion 29A in the cover plate 29 (referto FIG. 5A) between the intermittent advancements. Prior to picking upof the electronic component 16, a cover tape (not show in these figures)is peeled away from an upper surface of the carrier tape 7, pulledbackward, and stored into a storage container (not show in the figures)housed in the main body 4A.

A control system of the tape feeder 4 is constructed as described nextwith reference to FIG. 3. The tape feeder 4 contains feeder control unit24. The feeder control unit 24 is provided with motor controller 25,communication unit 27 and data storage unit 26. The motor controller 25controls motor 22 for driving the sprocket 21. The communication unit 27receives a control signal from the control unit 14 in the mountingapparatus 1, and transfers to the motor controller 25 such controlparameters as a rotation speed, an amount of rotation and the like ofthe motor 22. Accordingly, the motor controller 25 changes advancingspeed, advancing pitch, and so forth of the tape feeder 4 from time totime according to the kind of carrier tape 7 used, as directed by thecontrol unit 14.

In addition, the communication unit 27 performs a process of writing thedata sent from the control unit 14 into the data storage unit 26.Therefore, when sending a command regarding control parameters to themotor controller 25, all that is needed is a simple command indicatingthe kind of carrier tape used, so that the motor controller 25 canchange the advancing speed and the advancing pitch, if the data storageunit 26 stores tape data 15A of that particular carrier tape.

According to this exemplary embodiment as described above, a controlsignal is transmitted from the external device to the motor controllerwhich controls the motor, in the process of turning the sprocket andadvancing the tape intermittently by the drive mechanism capable ofcontrolling the rotation speed and amount of rotation using a motor asthe driving force. This structure makes it possible to easily change theadvancing speed and advancing distance of the tape by changing thecontrol parameters such as the rotating speed and the amount of rotationof the motor according to the electronic components to be mounted.Therefore, the mounting apparatus is flexibly adaptable to the change ofa type of electronic components it handles.

The stop position data 15B will be described next. In order to deliverelectronic components 16 borne on the carrier tape 7 to the correctposition, the pin 21A is required to stop at the proper position duringintermittent turning of the sprocket 21. However, there are certaindeviations in positions of the individual pins 21A of the sprocket 21due to manufacturing error. It is therefore necessary to correct thedeviations to bring each of the pins 21A to a stop at the rightposition. In this exemplary embodiment, the necessary correction is madeby using camera 12 to discern a position of each of the pins 21A on thesprocket 21, and to obtain an amount of deviation in the position.

The deviation in position of each of the pins 21A is measured in amanner as described hereinafter. FIG. 5A shows an upper surface of thecover plate 29 disposed above the sprocket 21. In FIG. 5A, dotted linesillustrate a tape bearing an electronic component in the deliveredposition. When the camera 12 takes a photographic image of the cutoutportion 29A without the carrier tape 7 set in position, it catches animage of one of the pins 21A located at or near a top area of thesprocket 21, and thus a position of this pin 21A is measurable.

The measurement gives pin offset data Δx and Δy representing a deviationof the pin 21A in the directions of the X-coordinate and theY-coordinate, respectively, from the regular position, as shown in FIG.5B. Offset data indicating a deviation of every one of the pins 21A fromthe regular position can be obtained in the same manner by measuring thedeviation of each pin one after another while turning the sprocket 21intermittently at intervals of a predetermined pitch. This can thusprovide a proper position of each of the pins 21A, that is, a stopposition where a turning motion of the sprocket 21 is to be interrupted(stopped) during the intermittent advancement of the tape, when each ofthe electronic components comes to the correct pickup location.Calculation is now made to obtain data for an amount of rotation of themotor 22 corresponding to each of the stop positions, as stop positiondata, and this stop position data obtained here is stored as offset datapeculiar to the particular tape feeder 4. Accordingly, the motor 22 iscontrolled and its rotation interrupted based on the offset data, so asto stop the pins 21A at the correct stop position all the time when thetape feeder 4 is under operation.

The control unit 14 performs a process of computing this data in themounting apparatus 1. Thus, the control unit 14 serves as a stopposition datacomputing unit. A result of the computation is stored inthe storage unit 15 of the mounting apparatus 1 as the offset datarepresenting amounts of positional deviations. At the same time, theseamounts of positional deviations are converted into another form ofoffset data with a number of pulses representing the amounts of rotationof the motor 22, and are sent to each of the tape feeders 4. The data ishence written into the data storage unit 26 via the communication unit27 in each of the tape feeders 4. Accordingly, the storage unit 15 ofthe mounting apparatus 1 and the data storage units 26 of the individualtape feeders 4 serve as stop position data storage units.

With reference to FIG. 5A through FIG. 6B, the feature described nextpertains to modes of the stop position data and the pick-up locationdata. As described here, offset data in the direction of theY-coordinate corresponds to the stop position data, and offset in thedirection of the X-coordinate corresponds to the pick-up location data.In FIG. 6A, measurement is made on positions of all the pins 21A of thesprocket 21 in the tape feeder, for which the data is to be prepared,and the measured pin positions are processed statistically to obtainmean positional data of the pin positions. In other words, mean valuesΣΔx/n and ΣΔy/n of the offset data Δx and Δy of the individual pins areobtained, and a mean value of the offset data is used as a single offsetdata peculiar to this particular tape feeder. Thus, the data processingcan be made easily by taking statistical process of the pin positionaldata and obtaining only one set of offset data peculiar to that tapefeeder.

FIG. 6B shows an example in which offset data is stored for each of thepins 21A of the sprocket 21. That is, the offset data Δx and Δy arestored exactly as they are measured, in the storage unit 15 as theoffset data (i.e. stop position data 15B and pick-up location data 15C)peculiar to these particular pins 21A in this example. In theillustrated instance, the stop position data is produced for theindividual pins 21A with their deviations reflected as they are.Therefore, these deviations are corrected in order to make the carriertape 7 stop at the right position at all times even if there are largedeviations in the pin positions of the sprocket 21 due to manufacturingerror.

What has been discussed in this preferred embodiment is an example whichuses distances of deviations of the pins 21A as the stop position data.However, the stop position data can also be obtained by taking aphotographic image of an area in the cutoff portion 29A with the carriertape 7 set in position, and measuring either a position of the recess 7Aor a position of the electronic component 16 disposed in the recess 7A.Offset data sets Δx and Δy obtained in this case are distances ofdeviations of the electronic component 16 from the regular pick-uplocation.

FIG. 7 shows a method of correcting the stop position of the carriertape 7 based on the stop position data and the pick-up location data, asdiscussed above, with the tape feeder 4 in operation. To stop the pins21A of the sprocket 21 at the right position during intermittentadvancing, the motor 22 is controlled according to the above-mentionedstop position data for proper positioning. In other words, the motor 22is stopped at a stop position corresponding to the position where thecorrection is made only by a distance of the offset data Δy in thedirection of Y-coordinate from the regular position in the data (shownwith a dashed line in the figure), when interrupting rotation of themotor 22.

Following the above process step, the transfer head 8 is activated for apick-up operation according to the pick-up location data when theelectronic component in the recess 7A is picked up with the transferhead 8. That is, the transfer head 8 is lowered after completing thepositioning by correcting the position of the transfer head 8 only by adistance of the offset data Δx in the direction of X-coordinate from theregular pick-up location in the data. Accordingly, displacement of thepick-up location due to the deviations in the pin positions of thesprocket 21 can be corrected effectively. The invention accomplishespositioning of the electronic component 16 into the correct pickuplocation, thereby decreasing pick-up errors by the transfer head 8.

According to this preferred embodiment, the tape feeder draws data on anamount of rotation of the motor corresponding to the right positionwhere turning of the sprocket is to be interrupted, based on the resultof measurement of pin positions of the sprocket, stores the data as thestop position data, and controls the motor based on the above stopposition data when the tape feeder is in operation. This structureallows the sprocket to stop at the right stop position at all times,thereby achieving accurate positioning of the electronic components intothe right pick-up location, alleviating difficulties in the positioningof the tape feeder, and improving the work efficiency.

1. A tape feeder for feeding an electronic component to a pick-uplocation in an electronic component mounting apparatus, said tape feedercomprising: a sprocket for engaging feedholes arranged at regularpitches along a tape, for advancing the tape intermittently; a drivemechanism having a motor for rotating said sprocket; a motor controllerfor controlling said motor; and a data storage unit for storing offsetdata to control a rotation amount of said motor, said offset dataincluding an actual measured intermittent stopping position of a pin ofsaid sprocket corresponding to a position when the electronic componentconveyed by the tape is located at the pick-up location.
 2. The tapefeeder of claim 1, wherein said sprocket has a plurality of pins, saidoffset data based on statistically-processed pin positions of all ofsaid pins of said sprocket.
 3. The tape feeder of claim 1, wherein saidsprocket has a plurality of pins, said offset data including individualpin positions of all of said pins of said sprocket.
 4. A method offeeding an electronic component with a tape feeder, said methodcomprising: intermittently advancing a tape conveying the electroniccomponent by rotating a sprocket using a motor, the sprocket engagingfeedholes arranged at regular pitches along the tape; measuring anintermittent stopping position of a pin of the sprocket corresponding toa position when the electronic component conveyed by the tape is locatedat a pick-up location in an electronic component mounting apparatus;generating offset data based on an amount of rotation of said motorcorresponding to the intermittent stopping position of the pin of thesprocket based on the result of said measuring of the intermittentstopping position of the pin of the sprocket; positioning the electroniccomponent at the pick-up location by controlling the motor to stop thesprocket at the intermittent stopping position based on the offset data;and storing the offset data in a data storage unit.
 5. The method ofclaim 4, wherein the sprocket includes a plurality of pins, saidgenerating of the offset data comprising statistically processing pinmeasured positions of all of the pins of the sprocket.
 6. The method ofclaim 4, wherein the sprocket includes a plurality of pins, the offsetdata represents data common to every intermittent stopping position. 7.The method of claim 4, wherein the sprocket includes a plurality ofpins, said generating of the offset data comprising generating dataindividually for all of the plurality of the pins of the sprocket. 8.The method of claim 7, wherein said positioning of the electroniccomponent comprises using the individual data for the pins to positionthe electronic component.
 9. An electronic component mounting apparatuscomprising: a transfer head for transferring an electronic componentfrom a tape conveying the electronic component to a substrate, and forplacing the electronic component on the substrate; a head drive unitincluding a control unit for controlling movement of said transfer head;and a tape feeder including: a sprocket for engaging feedholes arrangedat regular pitches along a tape, for advancing the tape intermittently;a drive mechanism having a motor for rotating said sprocket; a motorcontroller for controlling said motor; and a data storage unit forstoring offset data to control a rotation amount of said motor, saidoffset data including an actual measured intermittent stopping positionof a pin of said sprocket corresponding to a position when theelectronic component conveyed by the tape is located at the pick-uplocation; and a recognition unit for discerning the intermittentstopping position of said pin of said sprocket.
 10. The electroniccomponent mounting apparatus of claim 9, wherein said control unit isoperable to correct a location of pick-up location based on the actualmeasured intermittent stopping position of the pin discerned by saidrecognition unit.